Bogen CHB-35A PA amp

[punkykatt]

Hello all, One of my clients just gave me this amp. He said the school he teaches at was going to throw it in the dumpster.  Have any of you gentlemen performed any mods on this model Bogen to make it guitar frendly? Any ideas are appreciated.  Thanks Punky

[RicharD]

Plenty of potential to make a kick butt jalopy amp.  I'd start by making sure everything works first, ie. get it running happy as is.  Then I'd look into a more guitar friendly tone stack and cranking on V1.  It's output tubes are hard to come by so a gut job might be a plan too.  The chassis, OT and PT are all usable if in good shape.  Here's an old thread.
http://www.el34world.com/Forum/index.php?topic=7039.0
Search some of the other Bogen threads.  Lots of Bogens become geetar amps.

[Shrapnel]

Plenty of potential to make a kick butt jalopy amp.  I'd start by making sure everything works first, ie. get it running happy as is.  Then I'd look into a more guitar friendly tone stack and cranking on V1.

+1. Good advice.

It's output tubes are hard to come by so a gut job might be a plan too.

There IS new production 7868 tubes, just like there is on on the 7591A. Not as hard as it was to come by as it was a decade or two ago.

The chassis, OT and PT are all usable if in good shape.  Here's an old thread.
http://www.el34world.com/Forum/index.php?topic=7039.0
Search some of the other Bogen threads.  Lots of Bogens become geetar amps.

Good advice here too.

[eleventeen]

Can't complain about the price! Is it a CHB-33 or a CHB-35? One uses 7868's which are not that easy to get. The -33 model uses 6L6's. Both are excellent platform for tubing.

[Platefire]

I got a CHB-50 With 6L6's I made into a 5F6A. Also I got a Dukane PA ---Kinda like you--it came out of my Home town High School(Zwolle, La). I also made it into a 5F6A. One thing I've learned about 5F6A---them boogers are loud and clean, so I hardly ever use mine except in a big hall. Guess I need to do some Master Volume mods! Plate

[SoundmasterG]

I've got a thread going right now about a Bogen CHB100, which is double the output power of that amp you have there. The 7868's are easy to get from New Sensor, and they sound and perform good to boot. I'm still messing around with mine, having tried about 4 different preamp configurations and two phase inverter setups so far. Maybe because of the small chassis, you have to be careful with a ton of gain in the front end of these. The amp has a voltage doubler in the power supply and grid leak bias on the first stage, so those are some of the oddball things about it. I've gutted mine and started over, though I've kept the 7868 power tubes. They're pretty cool amps adn very tweakable.

greg

[punkykatt]

Thanks for the input guys. Hopefully I will have some time this weekend to mess with it. It looks to have all its original tubes, RCA preamps and Sylvania 7868`s for power tubes. I feel like a kid again waiting for Christmas day.
Punky

[jjasilli]

Plenty of info here.  Actualy I blundered into this Forum about 4 years ago, as a result of a google search for a schematic of the Bogen CHB-20.  (I haven't been able to find my way out    )

[dwp]

I got one the exact same way, schoolteacher friend said it had never been plugged in the 17 years he had been there. I ditched the oddball preamp and threw a 5E3 board in mine, it screams. A double power tweed deluxe. looks cool on my shelf with the entertaiment center too, tail out the back leads to a 1X12 screamin meanee. gets lots of compliments.......